A Familial Case of Achondrogenesis Type II Caused by a Dominant COL2A1 Mutation and ‘‘Patchy’’ Expression in the Mosaic Father

ß 2007 Wiley-Liss, Inc. American Journal of Medical Genetics Part A 143A:2815–2820 (2007) Clinical Report A Familial Case of Achondrogenesis Type II Caused by a Dominant COL2A1 Mutation and ‘‘Patchy’’ Expression in the Mosaic Father F. Forzano,1* M. Lituania,2 V. Viassolo,1 A. Superti-Furga,3 G. Wildhardt,5 B. Zabel,3,4 and F. Faravelli1 1S.C. Genetica Umana, Ospedali Galliera, Genova, Italy 2S.S. Medicina Fetale, Ospedali Galliera, Genova, Italy 3Centre for Pediatrics, University of Freiburg, Freiburg, Germany 4Children’s Hospital, University of Mainz, Mainz, Germany 5Bioscientia, Center for Human Genetics, Ingelheim, Germany Received 20 July 2006; Accepted 5 August 2007 Achondrogenesis type II (ACG2) is the most severe disorder from amniotic cells of the second and third fetuses revealed that can be produced by dominant mutations in COL2A1.We heterozygosity for a 10370G > T missense mutation (G346V) report on four pregnancies of an apparently healthy, in the COL2A1 gene. This mutation was also found in the nonconsanguineous young couple. The father had scoliosis father, as a mosaic. The couple had a fourth pregnancy, and as a child, and has slight body disproportion with short at 11 weeks fetal hydrops with a septated cystic hygroma trunk. The first child was born at 32 weeks and died were obvious. DNA from CVS demonstrated the same neonatally. In the second pregnancy, short limbs and fetal COL2A1 mutation. ß 2007 Wiley-Liss, Inc. hygroma were noted on ultrasound at 17 weeks’ gestation. Similar findings were observed in the third fetus. Clinical, radiological, and histological evaluation of the fetuses after termination of the pregnancies showed findings consistent Key words: achondrogenesis type II; COL2A1 mutation; with ACG2. Molecular analysis of genomic DNA extracted lethal skeletal dysplasia; mosaicism; recurrence How to cite this article: Forzano F, Lituania M, Viassolo V, Superti-Furga A, Wildhardt G, Zabel B, Faravelli F. 2007. A familial case of achondrogenesis type II caused by a dominant COL2A1 mutation and ‘‘patchy’’ expression in the mosaic father. Am J Med Genet Part A 143A:2815–2820. INTRODUCTION members as well. In rare cases, mutations that have resulted in Kniest dysplasia in children have been Achondrogenesis type II (ACG2) is a lethal skeletal found in a mosaic parent who either had Stickler dysplasia which is the most severe of the wide syndrome or mild spondyloepiphyseal dysplasia spectrum of disorders that can be produced by [Winterpacht et al., 1993; Spranger et al., 1994]. In mutations in COL2A1, the gene coding for cartilage- another family, recurrence of ACG2 in two fetuses specific collagen type 2. Mutations within the from the same clinically normal parents was inter- COL2A1 gene also cause Hypochondrogenesis preted as evidence for gonadal mosaicism [Faivre (OMIM 200610), Spondyloepiphyseal dysplasia et al., 2004]. (SED) congenita (OMIM 183900), SED Namaqualand Here, we report on a family in which three fetuses type (OMIM 142670), mild SED with precocious were affected by ACG2, and the father, who carries osteoarthritis, spondyloepimetaphyseal dysplasia the mutation in a mosaic state, shows an intermediate Strudwick type (OMIM 184250), Kniest dysplasia phenotype. (OMIM 156550), multiple epiphyseal dysplasia with myopia and conductive deafness, spondyloperiph- eral dysplasia (OMIM 271700), and Stickler dysplasia type I (OMIM 108300). The mutations responsible for *Correspondence to: Dr. F. Forzano, M.D., S.C.Genetica Umana, these phenotypes generally arise de novo—apart E.O.Ospedali Galliera, Via Volta 8, 16128 Genova, Italy. from Stickler syndrome type I, which is a milder E-mail: [email protected] condition and is frequently identified in family DOI 10.1002/ajmg.a.32047 American Journal of Medical Genetics Part A: DOI 10.1002/ajmg.a 2816 FORZANO ET AL. CLINICAL REPORT ultrasonography (ATL 3000, 5 MHz transducer), a viable fetus was recognized with circumferences of The couple first came to our attention after the first the head and abdomen appropriate for gestational child died soon after birth, and the second pregnancy age. All long bones had been measured in all was terminated. A COL2A1-related disease was extremities and showed that the limb shortening suspected based on X-rays and postmortem exami- involved all segments: femur length 39 mm (<1st nations. Both parents were of normal height, but centile; range 49.8–60.1 mm); tibia 32 mm (<3rd the father had scoliosis and showed slight body centile; range 44.4–54.0 mm); fibula 31.7 mm (<3%; disproportion (see description below). Based on range 43.1–52.9 mm); humerus 36.8 mm (<3rd these findings, counseling included the potential centile; range 45.5–55.0 mm); radius 31.9 mm for a recessive phenocopy. Somatic mosaicism was (<3rd centile; range 37.8–47.3 mm); ulna 36.4 mm also considered, although deemed less likely. The (<3rd centile; range 43.2–53.1 mm). The foot length couple had two additional pregnancies, which were was 48 mm (<3rd centile; range 51.4–64.3 mm) and terminated. the femur length/foot length ratio was 0.81 (<3rd The father of this family is 36 years old, and in centile). generally good health. He wore an orthopedic corset Multiple anomalies included: micrognathia, fetal as a child for scoliosis, and a ‘‘genetic disorder of the skin redundance in the neck and thorax region, and a spine’’ was suspected at that time, but no further ‘‘bell-shaped’’ thorax. The spine had an ovoid shape examinations were performed. and flattening of vertebral bodies. This pregnancy He is now 165 cm tall and shows slight body ended with preterm labor at 32-week gestation and disproportion with long limbs and short neck delivery of a 1,700 g male who died in the newborn and trunk. X-rays (Fig. 1) show normal femoral period. There was a short, thick neck, flat face with a heads, pelvis and lumbar vertebrae, and some deep nasal bridge, micrognathia, and short limbs. thoracic vertebrae show mild flattening and anterior Measurements were: total length 33 cm; vertex- wedging. sacrum 23 cm; upper limb: humerus 6 cm, forearm The first pregnancy of the couple (maternal age 6 cm, hand 4.5 cm; lower limb: femur 6.3 cm, lower 30 years) was evaluated at 28 weeks and 5 days leg 7 cm, foot 5 cm. Radiographs showed a bell- for suspected abnormal development of fetal limbs shaped thorax, platispondily, and wide femural and and mild polyhydramnios. With transabdominal humeral metaphyses (Fig. 2). Autopsy identified a FIG.1. Radiographs of father’s spine. Note mild flattening and anterior wedging of some thoracic vertebrae and normal femoral heads, pelvis and lumbar vertebrae. FIG.2. Ultrasound scan and postnatal radiographs of fetus 1. Note redundant skin (arrows on the left), platispondily (arrows on the right), bell-shaped thorax, wide femural and homeral metaphises. American Journal of Medical Genetics Part A: DOI 10.1002/ajmg.a ACHONDROGENESIS TYPE II 2817 FIG.3. Ultrasound scan of fetus 2. Note large and septated nuchal cystic hygroma (arrows; longitudinal and axial scans) and short femur. patent ductus arteriosus, foramen ovale, and dilated 18 mm (<3rd centile; range 19.6–27.2 mm). The left ureter. measurements of the other long bones were between The same 32-year-old mother was referred at the 5th and the 10th centile. Micrognathia was also 16 weeks of pregnancy for fetal karyotyping (amnio- present. centesis), which was 46,XX. At ultrasonography, the The pregnancy was terminated at 18 weeks fetus showed a large and septated nuchal cystic gestation. Postmortem examination showed a hygroma associated with hydrops and hyperechoic female fetus affected by a marked rhizomelic bowel (Fig. 3). Fetal biometry of the head was shortening of limbs. There was a prominent fore- appropriate for gestational age. All long bones were head, frontal bossing, and depressed nasal bridge. below the 3rd centile (micromelia): femur length Measurements were: cranial circumference (CC) 13.5 mm (range 16.5–24.0 mm); tibia 10.3 mm (range 17 cm; thorax circumference (TC) 14 cm; abdominal 13.3–20.5 mm); fibula 10 mm (range 12.8–20.0 mm); circumference (AC) 15 cm; upper limb: humerus humerus 13.5 mm (range 16.7–24.2 mm); radius 3 cm, forearm 3 cm, hand 2.4 cm; lower limb: femur 9.9 mm (range 13.0–20.3 mm); and ulna 10.4 mm 2.5 cm, foot 2.4 cm. Histologic examination of the (range 14.5–22.0 mm). Pregnancy was terminated at knee growth plates showed reduced and disorgan- 17 weeks gestation. ized columnar chondrocytes. Scans are shown in The couple’s third pregnancy (maternal age Figure 4. 33 years) underwent fetal karyotyping at The couple’s fourth pregnancy was screened at 17 þ 3/7 weeks. The circumferences of the head 10.6 weeks for prenatal diagnosis by chorionic villus and abdomen were appropriate for gestational age. sampling. Transvaginal ultrasonography showed a All long bones showed that only the proximal septated nuchal cystic hygroma with enlarged segments were shortened: femur length 20.4 mm jugular lymphatic sacs (see Fig. 5), and generalized (<3rd centile; range 19.4–27.2 mm) and humerus fetal hydrops developed 1 week later. Amniotic fluid, FIG.4. Ultrasound scan of fetus 3. Note micrognathia (arrow) and short femur. American Journal of Medical Genetics Part A: DOI 10.1002/ajmg.a 2818 FORZANO ET AL. FIG.5. Ultrasound transvaginal scan of fetus 4. Note increased nuchal translucency (left, longitudinal scan) and septated nuchal cystic hygroma (right, axial scan). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.] fetal biometry (CRL 45 mm), and heart rate were MATERIALS AND METHODS normal. Pregnancy was terminated at 11 weeks gestation and analysis of CV DNA was performed Ultrasonography has been performed with ATL for COL2A1 mutations.

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